The present invention relates to tools for installing pull type fasteners and more particularly to such tools which are pneumatically-hydraulically actuated.
The installation tool of the present invention is designed for use in setting two piece fasteners. The specific embodiment shown and described herein was designed for the installation of two piece blind fasteners such as that described in the co-pending U.S. patent application of W. Smith for "Two Piece Blind Fastener with Lock Spindle", Ser. No. 425,304, filed on Sept. 28, 1982. In the installation of such fasteners, it is desirable to have an installation tool which is compact and of a lightweight construction. While the use of plastic materials in the construction of such tools would be desirable in reducing weight, it is difficult to provide satisfactory seals and mechanically stressed connections in high pressure areas. In the present invention the installation tool has its housing and low pressure cylinder constructed of a lightweight plastic material and its high pressure cylinder constructed of ferrous or aluminum materials.
Two piece fasteners of the type noted are set by a relative pulling force between a pin and a sleeve or collar. Installation is completed when the pin is finally severed at a breakneck groove by the pulling force from the tool. At pin break, the loads built up in the tool could result in internal shock and vibration. In the present invention this shock is substantially eliminated by the use of a fluid dampening device.
In applying a fastener a nose assembly is secured to the tool. One type of nose assembly for setting lockbolts is shown in U.S. Pat. No. 4,347,728 issued Sept. 7, 1982 to W. Smith for "Apparatus and System for Setting Fasteners". A variation of the above nose assembly could be used for non-swage type, blind fasteners (of the type shown in the noted co-pending application). Thus in applying different types and sizes of fasteners it is common to utilize a variety of adaptors and/or entirely new subassemblies to accommodate different nose assemblies. In the construction of the present invention, the tool, being of a simple construction, can be readily disassembled and the replacement of only a single component can accommodate a number of different nose assemblies for setting a variety of fasteners.
The tool of the present invention utilizes low, pneumatic pressure to provide a significantly higher hydraulic working pressure which provides the necessary reciprocating pull force to the nose assembly for installing the fastener. The desired reciprocation selectively occurs in response to actuation of an air directional valve and a network of air logic passages. In the present invention the air directional valve is supported in a plastic housing which is connected to a plastic main housing of the tool. The air logic passages are substantially defined in the housings by molded grooves and ports. The latter design results in a generally inexpensive structure since, expensive secondary machinery operations are nearly completely eliminated.
In tools having hydraulic circuits the hydraulic fluid may have to be periodically replenished. In the present invention a generally straight fill path is provided with a large access in the pull cylinder to facilitate filling while inhibiting air entrapment.
Therefore, it is an object of the present invention to provide a new and unique pneumatic-hydraulic fastener installation tool being of a compact and lightweight construction.
It is another object of the present invention to provide a fastener installation tool of the above described type having a fluid dampening device to minimize internal shock and vibration at pin break.
It is still another object of the present invention to provide a fastener installation tool which can be readily adapted to accept different nose assemblies for setting different fasteners.
It is another object of the present invention to provide a fastener installation tool having a main air cylinder housing and air directional valve housing both made of a lightweight plastic and having a plurality of molded grooves and ports co-operating to define a network of air logic passages.
It is another object of the present invention to provide a pneumatic-hydraulic fastener installation tool having a construction facilitating filling with hydraulic fluid while inhibiting air entrapment.
It is a general object of the present invention to provide a new and improved pneumatic-hydraulic fastener installation tool.